Here's a little info on the 3rd Regiment and Camp Weld. Regiments and companies came and went continually so it would be harder to pinpoint exact numbers. A regiment did not necessarily have all of it's companies together at one time.
Specific Colo. Cav. line units (besides the headquarters) known to occupy Camp Weld:
1st Regt, Co. C, Sep-Dec 1863
Independent (Arty) Battery, Jan-Apr 1864
2nd Regt
- Co C, 1862
- Co D, Jan-Feb 1862
- Co E, Sep-Oct 1862
- Co G, Oct 1862
- Co I, Oct 1862
3rd Regt
- Co A, B and D, Jan-Feb 1863
- Co G, Jul-Aug 1863
(Source: Glen R. Scott, Denver Historical Trail Map, 1999, page 50.)
Third Colo. Regiment had 700 men at the battle of Sand Creek
Other Names: Chivington Massacre
Location: Kiowa County
Campaign: Sand Creek Campaign (1864)
Date(s): November 29-30, 1864
Principal Commanders: Col. John Chivington [US]; Black Kettle, Cheyenne
Forces Engaged: Third Colorado Regiment (approx. 700 men) [US]; 500 Cheyennes and a few Arapahos
Estimated Casualties: Total unknown (US unknown; I 200)